The present invention is directed to ink compositions and, more specifically, the present invention relates to hot melt inks with for example, a melting point of between about 25.degree. C. and about 50, and preferably about 40.degree. C., and which inks are especially useful for acoustic ink printing, processes and apparatuses, reference, for example, U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, U.S. Pat. No. 5,128,726, U.S. Pat. No. 5,371,531, the disclosures of which are totally incorporated herein by reference, including especially acoustic ink processes as illustrated in some of the aforementioned copending applications and patents, such as an acoustic ink printer for printing images on a record medium.
The inks of the present invention in embodiments thereof are comprised of (1) a liquid non-aqueous vehicle with for example, a boiling point of higher than, or equal to about 150.degree. C. (Centigrade) and lower than, or equal to about 350.degree. C., and more sepcifically from about 175 to about 325, and yet more specifically from about 225 to about 300 degrees Centigrade, with a low acoustic loss, which enables for example, a reduction, or minimzation of energy consumption, and which acoustic loss is below, or about equal to about 60 dB/mm, (2) a solid color spreading compound, or paper additive contained in the substrate, such as the paper pores, and which compound has a melting point of lower than, or equal to about 75.degree. C. and preferably between about 30 to about 74.degree. C., and with a low acoustic loss value of below about, or equal to about 100 dB/mm, (3) a nitrile liquid crystalline compound, (4) a light fastness UV absorber, (5) a light fastness antioxidant, (6) and a colorant such as a dye, a pigment or mixtures thereof. More specifically, the present invention is directed to semi-solid hot melt acoustic ink compositions comprised of (1) non-aqueous liquid vehicles with a boiling point of higher than about 150.degree. C. and lower than about 350.degree. C., preferably between about 170 to about 300.degree. C., and with low acoustic loss, and which acoustic loss is below about, or equal to about 60 dB/mm, and preferably in the range of between about 5 to about 40 dB/mm, (2) a non-aqueous solid, preferably cyclic additive with a melting point of lower than about 75.degree. C. and preferably between about 30 and about 74.degree. C., and with low acoustic loss and which acoustic loss is below about, or equal to about 100 dB/mm, and preferably in the range of between about 25 to about 80 dB/mm, (3) a liquid crystalline nitrile compound, (4) a UV absorber, (5) an antioxidant, and (6) a colorant, and wherein there can be generated with such inks excellent developed images on plain and coated papers with acceptable image permanence, excellent projection efficiency on transparencies without a post fusing step, and excellent crease resistance, and wherein the inks possess acceptable, and in embodiments superior lightfastness, and superior waterfastness. Moreover, in embodiments of the present invention there is enabled the elimination, or minimization of undesirable paper curl since water is not present, or minium amounts of water may be selected in embdoiments, and it is preferred that there be an absence of water. When water is not present in the inks a dryer can be avoided thereby minimizing the cost of the acoustic ink jet apparatus and process.